Equalization device

US20150002096A1Inactive Publication Date: 2015-01-01YAZAKI CORP
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2015-01-01
Estimated Expiration
Not applicable · inactive patent

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Abstract

A microcomputer finds a variation in respective unit cells based on an output from a voltage detection circuit, and executes equalization by controlling FETs and connecting unit cells having high both-end voltages in the unit cells to discharge resistors to perform discharging when the variation in both-end voltages of the unit cells is greater than or equal to a prescribed value, or executes the equalization by controlling FET pairs and sequentially connecting charging capacitors to the respective unit cells when the variation is smaller than the prescribed value.
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Description

TECHNICAL FIELD

[0001] The present invention relates to an equalization device, and more particularly to an equalization device that equalizes both-end voltages of a plurality of unit cells connected to each other in series.BACKGROUND ART

[0002] In recent years, a hybrid electric vehicle (which will be referred to as an HEV hereinafter) that travels with the use of both an engine and an electric motor has widely spread. This HEV is provided with two types of batteries, i.e., a low-voltage battery of approximately 12 V for starting the engine and a high-voltage battery as a battery pack for driving the electric motor. The above-described high-voltage battery provides a high voltage by using a secondary battery such as a nickel-metal hydride battery or a lithium battery as a unit cell and by connecting the plurality of units cells in series.

[0003] Both-end voltages of the respective unit cells, i.e., a state of charge (SOC) varies while charging and discharging of the high-voltage battery ...

Examples

Embodiment Construction

[0029]An equalization device according to the present invention will now be described with reference to FIG. 1 and FIG. 2. FIG. 1 is a block diagram showing an embodiment of an equalization device according to the present invention.FIG. 2 is a circuit diagram showing particulars of the equalization device depicted in FIG. 1. As shown in the drawings, an equalization device 1 is a device that equalizes both-end voltages of n(n≧3) unit cells CL1 to CLn that constitute a high-voltage battery BH and are connected in series. Each of the unit cells CL1 to CLn is composed of one secondary battery in this embodiment, but it may be composed of a plurality of secondary batteries. The high-voltage battery BH is used as, e.g., a power supply of an electric motor in a hybrid electric vehicle that employs both an engine and the electric motor (both of them are not shown) as a traveling drive source, the electric motor is connected as a load to both ends thereof as required, and an alternator or t...